JPS59101303A - Manufacture of flitch - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] This invention belongs to the field of wood veneer assembly technology. In particular, the present invention discloses an invention relating to a flitch manufacturing technique in the manufacturing process of laminated veneers.

[Background technology] Laminated veneers are made by creating raw material veneers from relatively low-grade logs using rotary lace, etc., and then laminating them with adhesive (1) and sandwiching them between molds. It was produced by pressing to create a flitch and then slicing it.

Conventionally, when creating flitches, it has been common practice to press them at room temperature. However, when pressing at room temperature, it takes time to make flinches, resulting in poor manufacturing efficiency. The reason for pressing at room temperature is related to the curing characteristics of the adhesive used. In other words, when trying to heat cure the wood veneer, the heat conduction rate of the wood veneer is slow, so it only hardens in areas close to the mold surface, leaving the center unhardened.

Therefore, an attempt was made to adopt a high-frequency heating method in order to create a flitch so that heat could be transmitted to the center of the flitch.

However, when heating a laminate of raw material veneers between mold plates,
Since there are variations in the dielectric properties of the raw material veneer, the high-frequency applied voltage varies, and the raw material veneer cannot always be uniformly heated.

[Purpose of the Invention] This invention was made in view of the above-mentioned circumstances (2), and provides a method for manufacturing a flitch using a high-frequency heating method that enables uniform heating even if the dielectric properties of the raw material veneer change. The purpose is to provide

[Disclosure of the Invention] When creating a flitch using a high-frequency dielectric heating method, the present invention uses a plastic sheet, such as polyethylene, or By inserting polypropylene or fluororesin between the electrode and the raw material veneer laminate, the dielectric properties including the sheet can be adjusted to a constant level, and the heated object can be heated uniformly by the high-frequency applied voltage determined thereby. It is intended for heating.

Generally speaking, the technology employed in this invention may be based on conventionally known technology, but the mold plate used has a structure in which an electrode plate is disposed on or near the surface of the mold plate. The material of the main body of the mold board is not particularly limited, but plastic, wooden molds, metal molds, etc. are used. Then, the plastic sheet is placed on the surface of the electrode plate (3).

An explanation will be given below with reference to drawings shown as examples.

Figure 1 is a schematic diagram showing the clamping state, 3.4 is a mold plate, 2
1 is a laminate of raw material veneers, and 1 is a plastic sheet.

Here, the thickness of each layer is dlJdJ#d as shown in Figure 2.
3, and the corresponding permittivity is ε2. ε2゜ε3
Then, the overall dielectric constant ε is given by the following formula.

Here, if the electric flux density is D, then the high frequency applied voltage ■ is determined by V=D·ε.

In this way, even if the veneer laminate 82, which is the object to be heated, changes depending on the moisture content of the veneer, the ε2 of the plastic sheet. ε1
By choosing appropriately, the dielectric constant of the dielectric material with plastic sheets inserted above and below can be kept constant (4), and the high frequency applied voltage determined by this can be determined.

Note that the amount of heat generated during high-frequency dielectric heating is generally expressed by the following formula.

However, + two frequencies [■Il] ε: Dielectric constant of the heated object -5: Dielectric power factor of the heated object V: Applied voltage: The distance between the electrodes or more is used to manufacture flitches by heating and compacting using a high-frequency heating method. The possibility of

Example: The size of the raw material veneer is 300 x 600 m, and the number of laminated sheets is 1.
The flitch was manufactured under the following conditions: 00 sheets, a pressing pressure of 15 kg/cn, a high frequency applied voltage of 100 OV (current: 1.5 A), and a heating time of 5 minutes.

As a result, the results shown in Table 1 were obtained. By changing the dielectric properties of the raw material (5) veneer and changing the thickness of the plastic sheet accordingly, we were able to keep the amount of heat generated constant.

[Effects of the Invention] As explained above, in the flitch manufacturing method for manufacturing a laminated veneer, the flitch is manufactured under high frequency heating, and the surface of the pressing mold is coated with plastic on the surface. The method is characterized by comprising an electrode on which a plastic sheet is arranged, and the thickness of the plastic sheet is determined so that the dielectric properties of the total of the laminate of the plastic sheet and the raw material veneer are constant. Even if the dielectric properties of the raw material veneer changed, uniform heating could be achieved.

(6) Table 1 (7)

[Brief explanation of the drawing]

FIGS. 1 and 2 are schematic diagrams showing the clamping state in this invention. 1 is a plastic sheet 2 is a laminate of raw material veneers 3. 4 is a mold patent applicant Matsushita Electric Works Co., Ltd. Representative Patent Attorney Toshimaru Takemoto (2 people) (8)

Claims (1)

[Claims] (1) In the flitch manufacturing method for manufacturing laminated veneers, the flitch is performed under high-frequency heating, and the surface of the clamping mold is composed of an electrode with a plastic sheet placed on the surface, and the plastic sheet is The thickness of the sheet,
A flitch manufacturing method characterized by determining and pressing the laminate of a plastic sheet and raw material veneer so that the total dielectric properties of the laminate are constant.